T-square.



y y of Fig.

WTED TATE PATENT @FFKGE.

SVEN JULIUS CARLSON', OF MIDDLETOVJN, CGNNECTICUT, ASSIGNOR OF ONE-HALF TO HELMER I. CARLSON, OF h IIDDLETOWN, CONNECTICUT.

T-SQUARE.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Application filed May 4, 1917. Serial No. 166,470.

To all whom it may concern:

Be it known that I, SVEN JULIUS GARL- soN, a citizen of the United States, residing at Middletown, in the county of Middlesex and State of Connecticut, have invented certain new and useful Improvements in T-Squares, of which the following is a specification.

My invention relates to improvements in T-squares, and the object of my improvement is to produce a T-square or attachment that can be applied to T-squares already in use, whereby the T-square structure is self-alining relatively to the drawing board, due to the action of a spring device that is attached to one end of the straight edge portion, that holds the crossmember or head member that is positioned at the other end thereof, in proper operative position, with the inner edge in contact with the opposed lateral edge of the the cross-member or head member and ad.

jacent parts.

Fig. 3 is a similar view of the right end, showing the spring device and adjacent parts.

Fig. 1 is a sectional view on, the line w w of Fig. 2.

Fig. 5 is a sectional view on the line Fig. 6 is a plan view, on a considerably reduced scale of a modification of the T- square in which the rollers are omitted from the head member.

My improved T-square comprises a T- square body made preferably of wood, composed of a straight edge portion 10 for extending over the face of the drawing board 11 and provided at the left end with a head member or cross-member 12 that extends across the straight edge portion on the underside, and in addition to the said body there are certain attachments that are applied to the said body and others for cooperating therewith that are applied to the drawing board.

The attachments to the drawing board 11 consist of a pair of tracks to be applied to the lateral edges, the left track 13 being attached to the left lateral edge and the right track 1st being attached to the right lateral edge.

As shown the tracks 13 and 14: are made of angle iron and they are positioned so that on each side there is an outwardly directed bearing edge 15 suitable for coiiperating with grooved rollers 16 that are provided on the attachments for the T-square body.

These last named attachments comprise a frame 17 at the left for a pair of rollers 16 and on the right there is the spring device 18 provided with a roller 16.

The frame 17 comprises an elongated, plate-like body that is secured to the inner edge of the head 12, and which is provided at both ends with a pair of inwardly directed ears 20 in spaced relation, between which the rollers 16 are positioned, the rollers being operatively connected thereto by pivotal pins 21.

The pair of rollers 16 at. the left cooperate with the left track 13 and serve as the bearing members for the head 12 in cooperation with the lateral edge of the drawing board structure. The frame 17, as mentioned, is secured to the inner edge of the head 12, and, as shown, extends along the greater part. of the length of the said head, and crossing the straight edge portion 10. By extending the frame 17 above the top face of the head 12 on each side of the straight edge 10 a higher position is obtainable for the car 20 that supports the roller 16 than would be possible if the .top face 19 of the said frame were flush with the top face of the head 12. As constructed, the said top face 19 is interrupted where it crosses the straight edge 10 by a recess of sufficient size to house the straight edge 10.

The spring device 18 comprises a housing 22 provided with inwardly directed arms for attachment to the end of the straight edge portion 10 of the T-square body and on the outer side is provided with a housing 24: for a plunger 25 that supports on its innor end a roller 16, the latter cooperating with the right track 14.

The housing 2% has a bore comprising a portion 26 extending the greater portion of the length that is of the same size as the body portion 27 of the plunger 25 and a portion 28 in the outer end portion 29 that is a fit for the reduced stem portion 30 of the said plunger The inner portion of the housing 2% is provided with a longitudinal slot 31 for a pin 32 positioned in the body portion 27, of the plunger that serves to prevent rotative movement of the plunger and to limit the inward movement thereof when removed from the drawing board.

The reduced stem portion 30 of the plunger is made of sufficient length to permit. a spring 33 to be mounted thereon.

The said spring 33 tends to drive the plunger and roller inwardly so as to hold the right roller engaged with the track and therebyoperates to hold the head 12 in cooperation with .the opposed edge of the drawing board through the medium of the rollers 16 and track 13.

The tracks 13 and 14 are preferably p0; sitioned so that the straight edge portion 10 of the T-square body will be positioned slightly above the face of the drawing board 11 at the ends so as to provide clearance for any thumb tacks that may be in place along the edge portions of the drawing board.

In the modification shown in Fig. 6 the head portion 12 abuts directly against the lateral edge of the drawing board 11, the rollers 16 being omitted.

In use, the spring device holds the straight edge portion in position for use, independently of the operator, in all positions, as the same is raised and lowered, the T-square structure being self-alining.

The attachments for effecting the selfalinement, as described, are adapted to be attached to T-squares such as are in common use, without change except that the length of the straight edge portion would be adjusted to fit the particular drawing board with which it. was to be used.

The pin 32 that serves as a guidepin in cooperation with the slot 31 in the housing 24 for guiding the plunger 25 is extended through the plunger 25, passing across a space or recess in which the ri ht hand roller 16 is housed, the body portion serving as the shaft or pinion, supporting the said roller,

the end portion, projecting beyond the face of the plunger 25 serving as the guide pin portion.

, The laterally directed bearing portions of the guide rails or tracks 13 and 1 1 are square ended, with parallel top and bottom'faces,

and the rollers 16 are grooved to fit the same, being thus adapted to support the straight edge portion 10 clear of the drawing board and thumb-tacks, as mentioned.

I claim as my invention 1. A roller supporting device for use with a T-square, comprising an elongated frame suitable for being attached to the edge portion of the head of a T-square that is opposed to the edge portion of the drawing board so as to extend across the straight edge portion of the said T-square, and a pair of rollers operatively housed in the end portions of the said frame so as to travel along the said edge portion of tl e drawing board.

2. In combination, a T-square having a straight edge portion for extending across the face of the drawing board, and a head extending across one end thereof for'extend ing along one lateral ed 'c of the drawing board, the said head being provided with .a pair of rollers for engaging with the said edge of the drawing board, and a spring device mounted on the other end of the said straight edge portion, the said spring .device having a plunger provided with a roller and a spring tending to drive the said plunger inwardly so as to hold the said roller in engagement with the other lateral edge of the drawing board, and the said lateral edges of the drawing board having each a track for cooperating with the said roller and the said rollers and tracks beingoperative to support the said straight edge portion of the T-square in spaced relation to the drawing board.

3. A spring device adapted to be secured to the end of the straight edge portion ofa T-square for holding the head portion engaged with the edge of a drawing board, comprising a housing, a plunger and spring operatively housed therein, a roller supported by the said plunger and adapted to cooperate with a track on the said drawing board, the said housing having a longitudi nal guide-slot in the side wall, and a pin, supported by the said plunger, serving as the pivotal shaft for he said roller and having an extension that servesas a guide for the said plunger in cooperation with the said guide-slot.

SVEN JULIUS GARLSON. l Vitnesses:

N. L. Ronnn'rs, KATHERINE BOWEN.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

Washington, I). C. 

